NOAA Coral Reef Watch Coral Bleaching Thermal Stress Outlook (Experimental product) Background

3. Coral Bleaching Outlook (Based on Version 1 Outlook)

An experimental coral bleaching outlook algorithm has been developed to derive bleaching risk levels from the predicted thermal stress described in the previous subsection. Three levels of bleaching risk have been currently defined based on the relationship found between the intensity and duration of the retrospectively predicted thermal stress indices for 2000-2005 and the HotSpot and Degree Heating Weeks observations from the archived 2000-2005 CRW near-real-time coral bleaching monitoring data set. The three levels are color-coded (yellow, orange, and red) on a coral bleaching outlook map (Fig. 3) with the following meanings:

All colored areas:
                       predicted coral bleaching thermal stress areas
Orange-colored areas:
                       wide-spread coral bleaching likely
Red-colored areas:
                       severe coral bleaching likely

For comparison, NOAA Coral Reef Watch’s operational twice-weekly near-real-time satellite coral bleaching HotSpots and Degree Heating Weeks for the twice-weekly period of October 8-10, 2005 are shown in Fig. 4. Please note that the appearance of the observed large-scale high Degree Heating Week values in the Northwest Pacific is from the accumulation of HotSpots prior to October 8-10 and does not indicate the presence of large-scale high thermal stress (i.e., large area of HotSpots exceeding 1 degree-Celsius) during October 8-10 in the region. The HotSpot image in Fig. 4 shows the diminishing of thermal stress in the Northwest Pacific Ocean. This retrospective bleaching outlook (Fig. 3) predicts very well the global bleaching thermal stress conditions for Oct 6-12, 2005.